1. Field of the Invention
The present invention relates to a one-by-one type heat-processing apparatus and, more particularly, to a one-by-one type heat-processing apparatus for forming a film on the surface of a target object.
2. Description of the Related Art
Generally, in a process of manufacturing a semiconductor integrated circuit, film formation and patterning by photolithography are repeatedly performed for a target object such as a semiconductor wafer or a glass substrate, thereby forming a desired device on the target object.
Processing apparatuses used to form films on target objects include a batch type apparatus and a one-by-one type apparatus. The batch type heat-processing apparatus can process a large number of target objects at once. On the other hand, the one-by-one type heat-processing apparatus can process target objects one by one. These two types of apparatuses are properly selected and used in accordance with, e.g., the quality or type of a film to be formed.
A one-by-one type CVD apparatus used to form a film on a semiconductor wafer will be described below. As shown in FIG. 1, a CVD apparatus 10 comprises a processing vessel 11. A susceptor 12 is arranged in the processing vessel 11. A semiconductor wafer W can be placed on a support surface 13 of the susceptor 12. The semiconductor wafer W can be fixed by a fixing means such as an electrostatic chuck. A shower head section 14 is arranged above the support surface 13 to be parallel and opposite to the support surface. A processing gas supplied from a processing gas supply source (not shown) is supplied into the processing vessel 11 via the shower head section 14.
Film formation processing is performed by supplying the processing gas into the processing vessel 11 via the above-described shower head section 14 while keeping the process pressure in the processing vessel 11 and the wafer W at the process temperature. By this film formation processing, a film consisting of a predetermined material such as polysilicon or silicon oxide can be formed on the surface of the semiconductor wafer.
To obtain a large number of devices excellent in electrical characteristics in manufacturing semiconductor devices, films having proper characteristics must be formed. The in-plane uniformity of the film thickness of a wafer is the most important characteristic of them.
There are a large number of parameters to control the film thickness. These parameters include the process pressure, the process temperature, the supply amount of a processing gas, the wafer size, the size of each portion of a processing apparatus. These parameters are not independent of each other but related to each other. Therefore, it is difficult to uniquely determine the optimum values of these parameters. The optimum film formation conditions have conventionally been prepared from the results obtained by actually, repeatedly performing film formation processing under various design conditions for an apparatus and various processing conditions.
At present, as for 6" wafers, films can be formed with high in-plane uniformity of the film thickness of the wafers. In recent years, however, the diameters of semiconductor wafers tend to be increased. If the diameters of semiconductor wafers are increased from 6 inches to 8 or 12 inches, the film formation conditions for 6" wafers may not be directly applied to the wafers having larger diameters. In addition, thinner, higher-quality films are required to be formed due to demands for increases in integration and density of semiconductor devices. However, it is difficult to meet these demands by processing apparatus for 6" wafers.